Climate Prediction Center’s Africa Hazards Outlook August 25 – August 31, 2016
Despite slight decrease in rainfall in mid-August, flooding remains a threat in East Africa.
Heavy rainfall forecast over much of West Africa during late August.
1) Persistent, above-average rainfall since July has led to excessively wet ground conditions resulting in numerous floods, damages to infrastructure, displaced populations, and fatalities over the areas of Kassala, Darfur, Sennar, Kordofan, Al Gezira, Gedaref, and White Nile areas of Sudan, South Sudan, and Ethiopia.
2) Heavy rainfall over the past several weeks has triggered flooding and inundation along the Niger and Benue Rivers in Nigeria. Enhanced rainfall is forecast across much of West Africa during the next seven days, sustaining the risk for flooding into late August.
3) With heavy rains received over parts of Senegal, Mali, and southern Mauritania during July, there is a potential for increased number of locusts which may negatively impact cropping activities.
4) Increased locust populations in Yemen are forecast to migrate across the Red Sea into parts of Eritrea, Ethiopia, and Djibouti during August.
Note: The hazards outlook map on page 1 is based on current weather/climate information and short and medium range weather forecasts (up to 1 week). It assesses their potential impact on crop and pasture conditions. Shaded polygons are added in areas where anomalous conditions have been observed. The boundaries of these polygons are only approximate at this continental scale. This product does not reflect long range seasonal climate forecasts or indicate current or projected food security conditions.
Questions or comments about this product may be directed to Wassila.Thiaw@noaa.gov or 1-301-683-3424.
Heavy rains continue this week across Guinea, Senegal.
Heavy seasonal rainfall continued throughout many western Sahelian and Gulf of Guinea countries during the last seven days. According to satellite rainfall estimates, the highest weekly accumulations (>100mm) were received across western Senegal and northern Guinea, with numerous pockets of similar accumulations over Mali, southern Mauritania, Nigeria and northern Cote d’Ivoire (Figure 1). Light to moderate rainfall accumulations were also received further north into more arid regions of Mauritania, northern Mali, and Niger. Increased rainfall accumulations were registered further south Cote d’Ivoire and Ghana following a week where little to no precipitation was observed.
Since June, the evolution of seasonal rainfall across West Africa can be characterized as being persistently wet with no prominent pattern of abnormal dryness, or untimely dry spells to affect any regions. The observed areas that have performed near average or slightly below-average have been localized in nature, owing to lower totals compared adjacent regions where rainfall has been repeatedly heavy on a weekly basis. An analysis of the maximum consecutive weeks of above average (>120% of normal) rainfall shows several countries received as least 4 consecutive weeks of heavy rainfall in Guinea, Sierra Leone, Mali, Burkina Faso, southern Mauritania, northern Nigeria, and Niger (Figure 2). This has triggered numerous flooding events, and continues to sustain the risk of flooding and river inundation into the end of the month.
For the upcoming outlook period, precipitation models suggest the potential for band of heavy shower activity extending from central Mali eastward towards central Nigeria. This is expected to sustain the risk for flooding as high river levels and saturated ground conditions have been observed throughout the region.
Dryness developing across parts of Uganda, South Sudan.
In eastern Africa, several consecutive weeks of high rainfall accumulations over Sudan and Ethiopia since June have led to remarkably high seasonal moisture surpluses resulting in flooding, damages to infrastructure, displaced populations, and fatalities across much of the region. However, suppressed moisture conditions have developed towards the south which has already begun to affect portions of southern Ethiopia, southern South Sudan, and northern Uganda with seasonal percentiles now falling below the 10% level (Figure 3).
Comparison with remotely sensed vegetation health indices corroborates a shortage of available ground moisture, as conditions have been declining across the region over the past few weeks. Much of the dryness in northern Uganda and South Sudan has been associated with periods of little to no rainfall (dry spells) during July and August. For the upcoming outlook period, little change in the distribution of rainfall is forecast with enhanced precipitation expected towards the north over Ethiopia and Sudan, and suppressed precipitation expected towards the south over South Sudan and Uganda.
Satellite-Estimated Total Rainfall (mm) Valid: August 14 – 20, 2016
Figure 1: NOAA/CPC
Maximum Consecutive Weeks of Above-Average Rainfall (%) Since week of: May 29 – June 4, 2016
Figure 2: NOAA/CPC
90-Day Satellite Estimated Rainfall Percentile (%) Valid: May 23 – August 2, 2016
Figure 3: NOAA/CPC
